It is very common in the valve industry to secure a valve seat and a valve body through the agency of a valve seat retainer. One prevalent method of fastening a seat retainer to a valve body is through the use of screws which extend through screw holes in the retainer and are threadably received by bores in the valve body.
In recent years, it has become recognized that voids caused by screw holes in the valve seat retainer may enhance leaking at the valve-gasket interface, and efforts have been made to provide valve seat retainers with fully uninterrupted gasket faces. Furthermore, it has been recognized that many industrial valves are positioned between mating flanges during operation, and that it is necessary only to secure a valve seat retainer to a valve body during assembly, shipping, handling and installation. One prior art approach for holding the valve seat retainer in place on a valve body during these periods is by snap ring assemblies. However, for the most part, these prior art snap ring assemblies have not been fully satisfactory. Among other difficulties, retainers secured by prior art snap ring assemblies are frequently difficult for field service personnel to remove. When hit from the inside by a hammer or pried from a valve body with a screwdriver, such prior art valve seat retainers tend to wedge and bind.